[iOS] Default to device architecture when debugging.
[iOS] Default to device architecture when debugging.

Unless the application does not have a slice for the device's native architecture,
in which case it defaults to an arch that it does contain.

beni55/RubyMotion,hboon/RubyMotion,katsuyoshi/RubyMotion,beni55/RubyMotion,incbee/RubyMotion,katsuyoshi/RubyMotion,katsuyoshi/RubyMotion,beni55/RubyMotion,HipByte/RubyMotion,HipByte/RubyMotion,hboon/RubyMotion,jjaffeux/RubyMotion,HipByte/RubyMotion,jjaffeux/RubyMotion,incbee/RubyMotion,incbee/RubyMotion,katsuyoshi/RubyMotion,beni55/RubyMotion,hboon/RubyMotion,jjaffeux/RubyMotion,jjaffeux/RubyMotion,incbee/RubyMotion